


Jet Fuel Is Thicker Than Water

by Ononymous



Series: Christmas 2019 Stories and Requests [11]
Category: Undertale (Video Game)
Genre: Gen, Post-Undertale Pacifist Route
Language: English
Status: Completed
Published: 2020-01-05
Updated: 2020-01-05
Packaged: 2021-02-27 11:47:12
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,305
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22136530
Author URL: https://archiveofourown.org/users/Ononymous/pseuds/Ononymous
Summary: Someone whose entire M.O. is to hide their feelings behind aloof disinterest doesn't sound like the best idea for a last minute babysitter, does it? Well Tsunderplane's cousin doesn't agree with that. Even if Tsunderplane herself might...
Series: Christmas 2019 Stories and Requests [11]
Series URL: https://archiveofourown.org/series/1580731
Comments: 8
Kudos: 12





	Jet Fuel Is Thicker Than Water

**Author's Note:**

  * For [CoramDeo](https://archiveofourown.org/users/CoramDeo/gifts).



The airports nearest to Mount Ebott had a particular headache to deal with once the monsters came to the surface, namely the monsters that could fly. In theory they never flew high enough to interfere with air traffic beyond the occasional drone, but the nature of some of them meant any time they were not in contact with the ground, they appeared on radar screens, regardless of how fast or not they were going. And in the air traffic control of Dethre and Tenot airports, one such blip was holding steady on the corner of two streets that were freshly built.

"Ugh," said that blip, "I've got to stop agreeing to favours without knowing the details ahead of time.

The airplane hovered five or six feet off the pavement, waiting for her agreed rendezvous. Out of boredom she flicked through her standard radio frequencies, but there was nothing but talk radio and the occasional check-ins from Dethre Airport confirming she wasn't going to get in the way of the transcontinental flight paths, something her automated transponder dealt with effortlessly after King Asgore received a letter about her last manual response. She still didn't understand why the humans thought it was so hostile when she clearly signalled her desire to maintain cordial relations with them in the subtext.

"I'm giving her ten minutes and then I'm flying over to the lake to see what Dub's up to-"

"Tsunderplane, there you are."

The hail didn't sound very enthusiastic, but Tsunderplane knew better. Her maneuver thrusters rotated her on the spot so she was facing a large wooden cart trundling towards her without any obvious sign of propulsion.

"Hi Daruderwagon," she said to her cousin, "how's Grandma Kuu?"

"Oh, same as always," said Daruderwagon, "always just observing the world going by, trying to make observations. And yet when you try and ask her about them she gets all flustered and says you're distracting her. Honestly I've given up probing. Less bother for me that way."

"Hmm," said Tsunderplane with projected disinterest. "So what can I do for you."

"I wouldn't have asked if it wasn't necessary, it'd be easier if I didn't, but, well, you need to meet someone. Izzy?"

"Beep beep!"

Daruderwagon's back door fell open, forming a ramp. With a roaring engine a car large enough to be a child's go-kart dismounted, scooted up the street before dramatically spinning around and returning to the other vehicles, engine rumbling impatiently.

"I don't think you've met him before. This is my son, Isecar."

"Oh. Well, hello I guess."

"Izzy, say hello to your cousin."

"Beep beep!"

"Still young, hasn't learned meatspeak yet," said Daruderwagon, "his father insisted on a modern name for him just to stay relevant. It was easier to agree than argue with him. Well I hope he doesn't feel dated in the future. I'll worry about it if it comes up then. Don't want a pain in my axel unless I need it."

"Okaaay. And what do you want me to do?"

Daruderwagon backed up a bit. A squeaking noise came from one of her wheels. "Need to visit Doctor Drake for a little grease. Well he'll have me up on that lift of his and then Izzy's at that age where he's full of high-octane gas and he'll just race all around the waiting room and I can't restrain him. Can you keep an eye on him him until I get back?"

"Uhh..."

"Beep!" Isecar drove up under Tsunderplane, bouncing on his front wheels to reach her.

"Oh look, he likes you. Okay, gotta go. See you later."

"But-"

But Daruderwagon had swivelled around and was squeaking back up the street. Tsunderplane carefully backed up to look at her new responsibility.

"...beep?"

"My thoughts exactly, kid."

* * *

Not wanting to overload her engines with excess cargo, Tsunderplane had let Isecar follow her to a nearby park. The hope was that he'd take the hint and drive around on the grass. The hint remained undisturbed.

"Beep beep!"

"Look kid, I'm not great with land types. Keep trying to ground me, y'know?"

"Beep?"

"Well yeah, can't get up to a great speed Underground, can you? It was great to stretch my wings."

"Beep beep!" He drove up to the nice cream stall. His rear windscreen wiper wagged.

"Hello, little fellow!" chirped the Bunny. "You looking a nice cream?"

"Yeah, no," interjected Tsunderplane, "all that sugar will gunk up his engine and his mother will shoot me down. Got anything with a more hydrocarbon structure?"

"Uh, no, can't say I do. Sorry, ma'am."

"Don't ma'am me, buster-"

"Beep..." water sprayed into Isecar's windscreen.

"Oh great, now I have to deal with him being told no. Thanks, idiot."

"You're... welcome?"

It was quite the struggle to coax him away, his engine making a whining noise the whole time. Fortunately out of sight meant out of mind, and by the time the stall was out of his rear view mirror the engine was running more smoothly. Eventually they came across a stone block used as seating. No back, perfect for her wings.

"Listen, Izzy. I'm just gonna cool my jets a little, okay?" She performed a vertical landing to do just that. "Go zip around the grass for a bit or bit."

"Beep?"

"You know. Go fast. You never gone fast before?"

"...beep?"

"'How'? Well, you know how your speedometer has a bunch of numbers on it? See how high you can reach before you run out of room."

"Beep. Beep!"

Tsunderplane watched him drive over to one edge of the field in question, feeling the tension from extended interaction fade. The relaxation was interrupted by a distant 'Beep'.

"Yeah yeah," she called, "I'm watching."

The roar caught her by surprise. She saw his tires spin in place for just a moment, then shot off like he was full of nitro. The land types always could pick up speed a bit quicker than she could to start, but their limit was way lower than hers. Blades of grass went flying behind him as he tore dirt behind him. Just as the thought occurred to her that she hadn't advised him on when to break, she saw his body lean forward as he did just that, leaning into a spin as he edged up to the wall at the far edge, stopping with just the lightest of taps. This didn't discourage him, and soon enough he was racing back towards her, skidding to a halt with a little more grace than his outward journey had.

"...well that was kinda fast," she said. "I mean, for a car and all."

"Beep beep beep!" He leaned back on his rear wheels and soon his bumper was gently booping her nose cone. The shock almost knocked her off the bench.

"Hey hey hey, personal space!"

She regretted the gear-jerk reaction, as the hostility got his windscreen wet again.

"Oh, look, I didn't mean... it's not like I hate you or anything."

His wipers stopped. The engine sounded like it was on the verge of stalling. A clear sign of confusion.

"I mean, I was speaking the truth, wasn't I? For a car you were going really fast. I'm just... I'm just surprised you took my comment so cheerfully."

"...beep?"

"I mean, a lot of people don't get me. I tell them to leave me alone, and they actually leave me alone. What's up with that? Why can't they pick up on subtlety?"

"Beep beep."

"I dunno, kid. It's a thing you'll deal with when you grow up."

"Beep!"

"Well, thanks. I guess. That's kinda nice of you."

Tsunderplane was surprised to see his rear wiper wagging again. The possibility struck her that this little kid actually got her. Was that exciting or terrifying? Yes, she concluded. Better to keep aloof as possible just to avoid accidental exposure-

_Bounce!_

"What the-?"

Izzy fell back down to four wheels and turned around as the ball which had hit Tsunderplane's tail bounced down the path a bit. Soon a young bear and duck were coming up to her.

"Oh," said the bear, "sorry about that! Are you okay?"

"Yeah, I'm fine," she said, warm as Snowdin.

"Beep beep!"

Izzy had overtaken the ball, spun round and nudged it back to the others. The duck caught it adroitly in his wings.

"Ha ha, that's cool!" he said. "Hey, mind if your kid plays with us?"

"He's not-" Manual override engaged. "Well okay, if he wants to. No rust off my back.

"Beep beep!" Izzy drove onto the field, new friends in tow.

"That kid," mused Tsunderplane, "could befriend Jerry if he went crazy enough."

Tsunderplane's radar kept a check on the three boys as they ran around kicking the ball to each other. She noticed a funny quirk Izzy had where his wheels tended to slip on the ground when he was trying to pretend he was driving a different direction. It amused her. Not that she'd ever admit it. In the meantime, she was keeping in touch with the ground in another way.

"What do you mean, Dub?" she said through her radio. "I thought we were on for tomorrow night."

_"I said two marrows at night,"_ he responded. _"It was a pun."_

"Ugh, you spend too much time with Sans."

_"Well I could spend it with you, but you keep saying you want personal space!"_

"That doesn't mean space all by myself, silly! Geez, am I that opaque to you?"

"..."

Dub was saved from an impending inquisition by a very forlorn 'Beep'. Cutting off contact, Tsunderplane saw one of the three dots on her radar was making its way to her. Very slowly.

"Izzy?" She took off and hovered over.

"Beep... beep..."

Isecar was slowly approaching her. His windscreen washers were pouring nonstop, and his engine sounded miserable. His whole body tilted forward and to his left.

"Oh no oh no oh no, what happened? Your mom will kill me!"

Her nose cone got up close to his front left wheel. It was almost entirely flat, a long shard of green glass sticking out of it. His rim looked dented, the consequence of driving on a flat.

"Oh no, you shouldn't have driven on it, just called me over!"

"Beep..."

"Ugh, what to do what to do what to do..." Her front windows looked set. "Speed is critical. Hold still, Izzy."

He obeyed. She ignored his new friends coming up to them as she hovered over. A cargo crane lowered down and attached to him with a magnet, hoisting him off the ground entirely, wheels wiggling this way and that at the unfamiliar sensation of being entirely off the ground. Seatbelts descended and wrapped round him tight.

"Hey," said the duck, "what are you-"

_**WOOOOSH.** _

The two boys were knocked backwards as Tsunderplane soared through the air. The park fell away and behind them as she got to the safe distance to clear power lines. She could just about make out Isecar's 'Beeps', though she wasn't sure if they were beeps of fear or of excitement.

_"TSP-74205,"_ came her radio, _"This is Tenot ATC. Tsunder, you are reaching drone operating height and moving at speed without prior clearance. What's going on?"_

"Sorry Janet," she replied, "family emergency. Hiro can call King Asgore if there are any problems. Over and out."

No sooner had she cut off the radio than she spotted the medical clinic and began to descend again. Any hope of cleaning up this mess without an awkward conversation vanished as a squeak-free trundling noise emerged from the opening doors.

"Tsunderplane? What's- _Izzy?!_ "

Her spirit sank faster than she did. Fortunately Doctor Drake had the good decency to investigate where the sound of jet engines in full operation was coming from, and medical instinct took over.

"Hmm, glass foreign body, lacerations on forward passenger tire, light abrasion and indentation on rim and axel," he said. "Mrs Wagon, perhaps you should carry him inside, I'll call our mechanic."

The transfer was carried out silently. Or at least it sounded that way to Tsunderplane. Feeling terrible that this had happened on her watch. That her vulnerability had allowed it. Well never again, as long as she-

"-you, Tsun."

"Hmm? What did you say? Apart from hating me?"

"Hate you?" said Daruderwagon. "I'm thanking you! You got him here so quickly! Honestly, I should have warned you he's not used to places that aren't particularly cleaned up, I should get in touch with Captain Undyne about that. Oh, Izzy, it's okay, Mommy's got you now..."

"Beep..." he sniffled.

"I'm sorry," said Tsunderplane, for the first time in memory. "I should have..."

The conversation felt too awkward to continue. One for being open about their emotions, one for the effort of parsing them. So Daruderwagon started to follow Doctor Drake back into the clinic.

"Soon!"

Tsunderplane's dipping nose picked up altitude. "Huh? Izzy?"

"Beep beep! No! Soon!" He was trying to escape his mother, but his slashed tire was making it a challenge.

"Oh, bless him, his first meatwords!" she said. "He doesn't want to leave you. You must have had a real bond with him. Sweetie, Tsun has other things to do today. Maybe tomorrow when the doctor patches you up, okay?"

"Beep..." The horn had a sulky note now.

"I'll take that as an 'okay', mister," said his mother. "Thanks again, Tsun. Sorry it became a mess."

"No, it's okay. I enjoyed it."

These words too were rare. "Okay then. Call me later, I'll let you know how we get on."

She trundled inside, her son trying to get one last peak at his new friend. Tsunderplane maintained current altitude and position, not sure where to fly to.

"S-stupid kid," she said, reverting to form, "you weren't supposed to do that." A moment's silence. "Good on you."

**Author's Note:**

> Original Suggestion: How about a story that brings out Tsunderplane's warm side, or at least requires her to act out of type for at while?


End file.
